feat: remplacer section Notion apps par liens statiques Library/My Tasks/Trash/Help

- Section 'Notion apps' retirée
- Liens statiques en bas du sidebar (toujours visibles): Library, My Tasks, Trash, Help
- Nouvelle route /help avec page d'aide (raccourcis, guide rapide)
- Trash visible pour tous (plus de condition sur auth_method)
- 143 tests passent

app/routers/dashboard.py

@@ -314,6 +314,27 @@ async def accounts_page(request: Request):
     return template.render(**ctx)
 
 
+@router.get("/help", response_class=HTMLResponse)
+async def help_page(request: Request):
+    """Simple help / about page."""
+    from jinja2 import Environment, FileSystemLoader
+    env = Environment(loader=FileSystemLoader("app/templates"))
+    sidebar = _sidebar_data(request, [])
+    template = env.get_template("base.html")
+    return HTMLResponse(template.render(
+        **sidebar,
+        request=request,
+        content_html="""<div style="max-width:700px;margin:40px auto;padding:0 20px;">
+<h2>❓ FlowDeck Help</h2>
+<p style="color:var(--text-dim)">FlowDeck is a Notion-style workspace with Gitea/GitHub integration.</p>
+<h3>Getting Started</h3>
+<ul><li>Create a <b>Workspace</b> from the Workspaces page</li><li>Create <b>Pages</b> using the sidebar or <kbd>Ctrl+N</kbd></li><li>Connect <b>Gitea</b> or <b>GitHub</b> in Settings → Integrations</li></ul>
+<h3>Keyboard Shortcuts</h3>
+<table style="width:100%"><tr><td><kbd>Ctrl+N</kbd></td><td>New page</td></tr><tr><td><kbd>F2</kbd></td><td>Rename selected</td></tr><tr><td><kbd>Delete</kbd></td><td>Move to trash</td></tr><tr><td><kbd>Ctrl+K</kbd></td><td>Quick find</td></tr></table>
+</div>"""
+    ))
+
+
 @router.get("/accounts/settings", response_class=HTMLResponse)
 async def settings_page(request: Request):
     """User settings page — profile, forges, tokens."""